Carburetor



may 27,1924;

M. e.- CHANDLER CARBURETOR Filed April 28. 192; 2 Sheets-Sheet 1' M. G. CHANDLER CARBURETOR Filed April 28 1921 [Sheets-Sheet 2 Patented May 27, 1924.

MILFORD G. CHANDLER, OF CHICAGO, ILLINOIS, ASSIGNOR TO CURTIS B. CAMP, O'F OAK PARK, ILLINOIS, AND LYNN A; WILLIAMS, OF EVANSTON, ILLINOIS, JO'INT TRUSTEES.

CARBURETOB.

Application filed April 28, 1921. Serial No. 465,323.

ticularly to that type of carburetor arranged invention disclosed in for lifting fuel to the level of the carburetor by use of the suction obtained from the intake passage to the engine.

\Vith carburetors of this type, it is important to obtain a fuel lifting suction which is under some conditions greater than the suction existing in the intake passage to v the engine. This condition exists when the' throttle is rather widely opened and the speed of the engine is somewhat reduced through load. Under these conditions, the available directsuction may be insuflicient for lifting fuel from the low level source of supply to the carburetor. This invention is a modification and improvement upon the my Patent, No. 1,370,949, filed December 4, 1916, and issued March 8, 1921, wherein I have fully set forth the advantages to be derived from the augmentation of manifold or mixing chamber suction for fuel lifting purposes, and such advantages, therefore, need not be stated nozzle ets, the arrangement being such here.

In thepresent embodiment of my invention, I provide means in the form of a. small Venturi tube for obtaining a fuel lifting suctionwhich is greater than the suction existing in the body of the carburetor, the throat or some other point of high suction in this small Venturi tube being connected by a conduit with the upper space f throttle the mixture may be delicately regfucl reservoir for drawing fuel thereto from a low level source of supply.

One object of my invention is to provide means producing sufiicient suction for drawing fuel from the float chamber into the induction passage of the carburetor not withstanding the high suction existingin the upper spaces of the float chamber. The means herein provided comprise a small 'Venturi tube in the form of a nozzle which delivers fuel into a primary stream of air and a large Venturi tube comprising a secondary air intake into the throat of which the mixed fuel and air from the nozzle Venturi tube is delivered. The delivery to the throat of the large Venturi tube is accomplished through a movable member so shaped that it constitutes an anterior air valve with openings so located that as it moves to enlarge the opening through the large Venturi tube it delivers the emulsion of fuel and air always at the point of greatest suction in the large Venturi tube. By this combination of nozzle Venturi tube and large Veturi tube, a very high degree of suction is created for drawtube were not always present to a high t degree.

Another object of my invention is to pro- I vide a simple arrangement for injecting into the stream of air which is flowing into the carburetor an additional amount of fuel during the acceleration of the engine. This I accomplish by providing afWell within the movable part which forms the air valve,

thiswell co-operating with a piston-like member so as to force a portion of the fuel out of the well whenever the valve moves in the direction to enlarge the secondary air opening. This well is filled by fuel which has passed into the carburetor through the that omdeceleration, or during the closing movement of the air valve, an amount of fuel 'will be withheld from the air stream which is equal to the amount which is added on acceleration.

Another object of the invention is to provide a separate adjustment for idling purposes so that with substantially closed ulated to take care .of different amounts of valve stem leakages in different motors.

Other ob3ects of the invention will appear from the following specification and claims.

My invention is illustrated in the accompanying drawings, in which 7 Figure 1 is'an elevation;

Figure 2 is a section on the line 2-2 of Figure 1 and Figure 3 is a vertical section.

, turi tube 7.

' from the exhaust will be caused to circulate substantially entirely around the main intakev passage through the casing 5. Within the intake passage is mounted the usual throttle 15 below which is a spider 16 forming a bridge across the intake passage and supporting the fuel feeding mechanism centrally located in this intake passage. This mechanism comprises a small Venturi tube 9, to the throat of which fuel is conducted through ports 17 from the passage 18. The Venturi tube 9 is threaded into the bridge 16, and by means of a collar 20 holds a piston 21 in place against the bridge, the piston and the collar serving to enclose the ring-like passage by means of which fuel is conducted to the nozzle openings, from the fuel passage 18. A valve member 22 is cy-' lindrically shaped so as to have a close yet free working fit over the outside of the pis-' ton 21, this valve member also carrying a central tubular portion 23 which fits loosely with sufiicient' clearance over the downwardly projecting cylindrical end of the Veuturi tube 9 to perform the functions hereinafter described. A sleev e 25 is held within the valve member 22 and pressed against the base thereof by means of the spring 26, which acts to tend to close the valve member by forcing'it in a downward direction. The function of this sleeve inthe main will be brought out later, its object being to constitute a wall for the fuel well, and to assist in the dash pot action of the valve to prevent its fluttering. The lower portion of the valve 22 is provided with a plurality of radial passageways 27 connecting the inner chamber of the valve which communicates with the end of the Venturi tube 9 with the periphery of the valve at a point just above that at which the valve seats upon the throat of the large Venturi tube 7. There is a small step 30 formed in the external surface of the valve 22 at a point which splits the external ends of the openings 27 thus giving free communica- ,tion between themixing chamber of the carburetor and the external ends of the passageways 27, even when the valve 22 is tentirely seated.

Tn constructing the valve 22 it is found convenient to form the plug 32 of a separate piece which is soldered or otherwise secured eeann? in a circular opening'in the bottom of the valve. The large Venturi tube 7 is provided with a'plurality of ducts 34 leading from an annular space'35 maintained between the large Venturi tube and the wall of the casing 5, the function of which will be later described. The float chamber is provided with the usual float 3G in a well known way controlling the valve 37. ltuelenters the carburetor through a coupling 38 containing a screen 39 for straining the fuel before it enters the float chamber through the passa eways 40in the valve plug ll.

The structure just defined is attached to the lower. cover 42 for the float chamber, and may be completely assembled before attachment, attachment being made by means of screws 43', there being preferably a gasket 44 included between the body and the cover to prevent leakage. The member 38 is held in place-by a bolt 45, and is so ,shaped that it may be rotated to any position convenient for attachment to they fuel pipe.

The fuel feeding mechanism providing the idling adjustment comprises a passageway leading from below the surface of the fuel in the float chamber to an adjustable needle valve 51. This needle valve opens into a passage 52 which leads to a by-pass around the throttle 15. This by-pass is made up of three intersecting openings 52, 53 and 5d, and it may readily be seen that by provision of differently sized openings 52, and 54 the degree of suction on the fuel at the needle Valve 51 may be correspondingly varied. During the idling of a motor, the suction in the intake passage on the engine side of a. throttle is extremely high, and if fuel is fed directly from the float chamber into that part of the intake passage under such extremely high suction, the size of the fuel opening must be very small, and is therefore very easily clogged. By the an rangement herein described, the suction acting on the fuel passing the needle valve 51 may be reduced to any desired proportion of that existing above the throttle l5 and the opening at the needle valve may thus be materially enlarged so as to make clogging much less probable.

Tn this embodiment of my invention, float chamber is closed to atmosphere and fuel is lifted to the carburetor float chamber through suction which is maintained in t e float chamber for this purpose. In orde maintain a suction in the float chamb which is greater than that maintained the mixing chamber or intake passage o carburetor, ll provide a small Venturi 56 shown in Figure 2, which; has opening at its throat connected bya duct 58 wi the upper space of the float chamber. The inner end of the Venturi tube 56 normally projects into the carburetor air passage at a point above the upper of the valve member 22, but as that member rises, its outer surface comes opposite the end of the Venturi tube 56, the outer surface of the valve member 22 being conformed so as to partially obstruct the passage of air through the Venturi tube 56 under some conditions, the purpose of this being to control the float chamber suction toniaintain ij substantially constant for all conditions 0f operation of the carburetor. It is important that this float chamber suction be maintained substantially constant so that for changing conditions of operation, as from low engine demand to high engine demand, the float chamber vacuum will not materially change.

As an example, if the suction in the float chamber were allowed to vary materially between low engine demand and high engine demand, then it would follow that for any intermediate engine demand the float chamber suction would be required to have an intermediate value in order that a proper fuel feeding mixture would be delivered at the; intermediate demand. If, therefore, the engine demand were gradually changing, as would be the case if the speed of the car were either -increasingor decreasing, the float chamber suction would have to change in exact synchronism with the change in engine demand in order that for any one of the intermediate and changing conditions, a proper fuel feeding differential would be maintained to provide the correct mixture. Now,

whenever the carburetor throttle is quickly opened at a time when the car speed is comparatively high, the engine demand may be 'umped from its minimum, as represented y closed throttle, to its maximum, as represented by wide open throttle and high engine speed. It is impracticable'to provide sufficiently large openings that the float chamber suction can change through awide amount in such a short periodof time, and it is for this reason that T have found it important to provide means fot' maintaining the float chamber'suction substantially constant for all conditionsof engine demand. By a substantially constant float chamber vacuum is meant a vacuum which varies to a much less degree than does the mixing chamber vacuum during changes in engine demand.

By contouring the external surface of the This result is brought about by the control,

which the valve member 22 when properly contoured has over the quantity of-air flow ing through the Venturi tube 56, which in turn controls the degree of suction in the float chamber and consequently the fuel feeding differential. a rich mixture for starting when engine and carburetor are cold," I arrange a lever 60, which, by means of a dash adjustment 61, can be moved to obstruct the air intake to the Venturi tube 56. When this intake is entirely obstructed, the vacuum maintained in the float chamber will be the same as that in the carburetor body. This will give a very rich mixture, the vacuum in the float chamber thus being greatly decreased. When the lever 60 is in. a position in which it only partially obstructs the entrance to the Venturi tube 56, then the suction in the float chamber increases. The lever and dash adjustment therefore constitute a ready means of gradually leaning the mixture, as the heat of the engine and' carburetor build up. An anterior throttle 63 may be used in extreme cases for securing a very rich mixture for starting purposes.

The operation of this carburetor will now be described. The opening through the nozzle 9 is preferably made so small that for the lowest engine demand, even for idling, the suction created in the inner part of the valve 22 will besufficient to slightly lift that valve off its seat, and permit a small amount of air-to enter through the large Venturi tube 7. The suction is communicated to the inner part of the valve 22 through the clearance existing between the tube 23 and the downwardly projecting end of Venturi tube 9. This suction will therefore open the valve to such an extent only that thelsuction in the mixing chamber of the carburetor is relieved toa degree at which the suctiontending to open the valve and the spring pressure of the spring 26 tending to close it become balanced. The lower part of the valve 22 is so shaped that the expansion of the air passing upwardly through the large Venturi tube 7 and around the lower end of the valve 22 is at a rate to give the greatest enhancing etl'ect at the openin s in the valve 22. The throat of the large enturi tube is, of course, the point In order to provide of greatest restriction therein, and it will be noted as the valve 22 rises, the point of restriction rises with the valve. and is continually-just anterior to the point at which the mixture of fuel and air is fed to the large Venturi tube from within the plunger. This construction provides a material increase of suction just above the throat of the large .Venturi tube, that is, at the openings 27 through tlievalve 22, for all posi-' tions of the valve 22, even including the almost closed position which it assumes during idling. Y I

"Under .the idling conditions assumed in the preceding paragraph, the suction maintained in the mixing chamber of the carburetor is acting upon the Venturi tube 56 to create a high suction in the float chamber of the carburetor for lifting fuel thereto.

The suction produced by the Venturi tube delivering its emulsion into the throat of the large Venturi tube 7 so that there is within the'tube 23 a somewhat greater suction than is maintained in the mixing chamber of the carburetor. This is necessaryto provide a fuel feeding differential between the float chamber and the throat of the nozzle Venturi tube 9, under the conditions.

named. It has been found advisable to so adjust the ratio of suctions in the float chamber and in the'mixing chamber that for the lowest idling speed with throttle nearly closed, something less than the. required amount of fuel to give a properly explosive mixture will be delivered at the nozzle openings 17 of the Venturi tube 9. At this time, therefore, some fuel is delivcred through the idling opening 54:, and past the idling valve 51. The amount of air which is taken into an engine during idling around the stems of the intake valves changes materially with the wear of the engine, so that a carburetor adjustment sa'tisfactory for operating the engine when new, and when the valve stems fit the sleeves closely, will not be satisfactory for operation when the valve stems become worn. This leakage around the valves has very slight effect at other speeds than idling. The actual quantity of air passed in around the valves decreases as the suction in. the intake manifold decreases, and its proportion to the total amount of air taken in very materially decreasesas the total engine demand increases, therefore, it is unnecessary to provide a special adjustment to compeir sate for wear at other speeds than at idling. Justas soon as the throttle 15 is opened so as to expose the opening 54 to the vacuum below the throttle instead of to the vacuum above the throttle, no further fuel will be fed to the intake passage through the open- 5 ing 54 because the suction in the float chamher will be from that time on for all positions of the throttle greater than the suction on the opening 54. This will cause a slight amount of mixed air and fuel to pass hackw'ard through the needle valve 51 into the float chamber, but the opening at needle valve 51 is so small that the amount of mixed air and fuel which is drawn into the float chamber does not materially disturb the float chamber vacuum.

llt has'been stated that the space beneath the lower end of the piston 21, which operateswithin the cylindrical portion of the valvev22, contains liquid fuel. This fuel finds its. way into this chamber through the.

esser? space between the inner wall of the valve 22 and the outer surface of the piston 21. This is a very smallspace, and although of sufficient ,magnitude to permit the passage of fuel, it does not show in the drawings. Whenever the carburetor is in operation, the outer surface of the valve 22 is coated with a film of liquid fuel which travels upwardly with the air and is carried across the gap between the valve 22and the piston 21. Because the suction within the valve 22 is greater than that surrounding the piston 21, a portion of the fuel which travels up the wall of the valve 22 is drawn down between the piston andthe Valve into the space below the piston. This causes the space below the piston to very quickly fill with fuel when the carburetor is operated under steady conditions of engine demand. 7

When the throttle 15 is suddenly opened wide from a nearly closed position, the high suction of the manifold is communicated to the mixing chamber of the carburetor and, on account of the in-rush of air past the ends of the openings 27 ,in the valve 22, an extremely high suction is created in the space within the tube 23 forming a part of the valve 22. This suction is communicated to the interior chambers of the valve 22 through the space around the lower end of the Venturi tube 9 and consequently causes the valve 22 to rise. As the valve rises the fuel which was entrappedbeneath the piston 21 is forced and drawn upwardly through the space between the sleeve 25 and the piston 21 and is injected into the air stream through a series of openings or, if the quantity be sufficient, this fuel may be drawn into the stream of air passing through the primary Venturi tube 9 through the space surrounding the depending end of that Venturi tube. This extra amount of fuel which has been injected into the inrushing stream of air during the period immediately following the sudden opening of the throttle 15 provides a mixture correction which pracl tice has shown is important to secure proper performance durlng acceleration.

'When the englne is run at high speed with wide open throttle the demand is so great as to open'the valve 22 to its upper limit. This valve being downwardly pressed by the spring 26 has the effect to create a somewhat higher suction at high time at low engine demand. It thevacuum Venturi tube were not 1n some way controlled as to the amount. of air passing through it, this in creased suctlon 1n the m1xing chamber would of course create an increased suction in the,

top of the float chamber at higher engine demands. The externalsurface-of the valve 22, however, limits. the discharge from the inner end of the venturl tube 56. As heretofore pointed out, the surface of the valve 22 lllll the float chamber is thus-maintained sub-y stantially' constant. I

After the valve 22 has been lifted slightly above its normal seating position, air is admitted to the annular space 35 around the large Venturi tube 7 t-hrough'a plurality of openings 34. The function of admitting air around the large Venturi tube 7 is primarily to assist in the prevention of loading caused by unatomized and unvaporized fuel flowing into the cylinders and has this result because the admission of a film of air adjacent to the carburetor casing assists in the prevention of the collection of liquid fuel on the casing. Such liquid fuel as tends to flow upwardly along the inner walls of the large Venturi tube 7 is whipped off of the soinewhatsharpened upper edge by the high velocity of the air passing into the chamber around the outside of this Venturi tube.

Other features of this device are either common to the well known types of carburetor and need not be specifically described or will be readily understood from an inspection of the drawing. While I have shown and described my invention with respect to the details herein illustrated, I do not wish to be unduly limited thereto, many modifications being possible without depart ing from the spirit or scope of my invention.

What I claim is: r 1. The combination with a casing having a primary mixture intake passage, a secondary mixture intake passagehavingouter walls which flare gradually toward the interior of the carburetor, an automatic valve controlling the secondary air intake and mixture passage and having walls substantially parallel with the flaring walls of the passage and spaced therefrom, the primary 1n-' take passage communicating w1th the interior of said valve and discharging into the secondary intake passage at the periphery of said valve and near the anterior part of the space between the valve and the walls of the passage.

2. In a carburetor, the combination with a casing having primary and secondary air intake passages, a nozzle Venturi tube forming part of the primary air intake passage and having meanstherein for admitting fuel to form a primary mixture, a valve forming with the walls ofthe secondary air intake passage an annular space gradually expanding inwardly and varying also with the changes of position of the valve, said valve being provided with a passageway therethrough communicatin with the pnmary air intake passage an adapted to receive a mixture of air and fuel from the nozzle Venturi tube in the primary air intake passage and to deliver such mixture from the periphery of the valve intothe annular space between the walls of the valve and the secondary air intake passage at a point near the entrance to said space, the said valve being automatically movable to increase or decrease-the size of said annular space depend-" ing upon the flow of air past the valve.

3.'In a carburetor, the combination with a casing having primary and secondary air intake passages, anozzle Venturi tube constituting the primary air intake passage having means therein for admitting fuel to form a primary mixture and a large Venturi tube constituting the secondary air'intake passage, a movable member located within the large Venturi tube and having a passageway through it communicating with the discharge end of the nozzle Venturi tube and discharging into the large Venturi tube at the periphery of said movable member, said member being so shaped as to constitute the point of greatest restriction in the large Venturi tube immediately anterior to the position at which the fuel and air from the nozzle'Venturi tube are delivered into the large Venturi tube for all positions of said movable member and to form with the walls of said large Venturitube a passage which very gradually expands posterior to vthe point of entrance of the fuel and air therein.-

l. In a carburetor, the combination with primary and secondary air intake passages of a nozzle Venturi tube forming a part of the primary-air intake passage and having means therein for admitting fuel to form a primary mixture, said Venturi tube delivering the primary mixture into the carburetor body in theopposite direction to the flow of mixture to the engine served by the carburetor, a. valve forming a part of thelarge Venturi tube constituting the secondary air intake to 'said carburetor, said valve having an opening therethrough, the entrance to.

which is in communication with the discharge end of the nozzle Venturi tube and the exit from which communicates radially with the throat of the large Venturi tube.

5. A carburetor provided with a secondary air intake opening, a movable plunger in said opening, a fuel and air discharge port carried by said plunger and located therein near the point of greatest restriction in the secondary air intake passage, a'nozzle Venturi tube having means therein for admitting fuel to form a primary mixture discharging into said plunger, a piston within said plunger enclosing a space therein, and means to communicate the suction of the passage through said plunger with the space =en closed by said piston whereby the suction causes the opening of said plunger and a spring for opposing the movement of the plunger in the direction to open the intake passage..- T

6. In a vacuum-feed carburetor, the combination with a casing having primary and secondary air intake passages, a hollow movlll able member for variably restricting the passage of air through the secondary air intake passage, a Venturi tube forming part of the primary passage having means therein for admitting fuel to term a primary mixture, means to deliver the primary mixture from the discharge end of said Venturi tube to the periphery of the movable restricting member for the secondary air intake passage, a float chamber for the carburetor, a vacuum Venturi tube extending into the interior spaces of the carburetor and terminating adjacent the movable restricting member for the secondary air intake passageway, a duct extending from the throat of the vacuum Venturi tube to the upper space of said float chamber for creating a suction in the upper space of said float chamber for lifting fuel thereto, said movable member carrying a surface for variably cutting oil the discharge opening from said vacuum Venturi tube, whereby the suction produced in the lloat chamber may be maintained less than the suction produced in the fuel delivery Venturi tube.

7. lln a vacuum teed carburetor, the combination with a casing having a passage theret-hrough, a part of which forms a secondary air inlet, a valve member normally substantially closing said secondary inlet and movable in said passage by the suction therein, the opening into said casing normally substantially closed by said valve and having cross-sectional areas which progres sively increase in the direction of flow of air into the carburetor, said valve having cross-sectional areas which progressively increase in the same direction and having a wall substantially parallel with the flaring wall of the entrance to the intake passage, means to deliver an emulsion of fuel and air from the periphery of said valve substantially at the circle of greatest restriction in said intake passage so that as the valve member moves to enlarge the passage the emulsion will be continuously delivered to the entrance passage at substantially the point of greatest restriction therein, the movement of the valve member being such as to always create a restriction in the intake passage suliicient for maintaining, on

the posterior side of the valve member with in the body of the carburetor for all engine demands, a suction sut'licient for creating an adequate fuel lifting suction, a fuel chamber for supplying fuel to the carburetor and a communication between upper space of. said ituel chamber and t e carburetor intake valve mom or tor passage posterior to sai maintaining a suction he fuel chamber for lifting fuel to it from a source lower level. v

8. in a carburetor, combination wth an air intalre passage, a valve in. said passage having a therein and a Lacuna? primary mixture passage therethrough discharging at the periphery of said valve, \a piston in said valve forming a closure for said chamber, means for supplying fuel to said chamber and a discharge passage lrom said chamber to the periphery of said valve whereby when the valve is opened fuel will be discharged from said chamber as well as from the primary, mixture passage through the periphery of said valve into the stream ot'air passing into said carburetor. i

9. An automatically variable secondary air intake for carburetors controlled by engine suction consisting of two parts relatively movable along a common axis and having an annular space which increases in cross sectional area in the direction toward the interior of the carburetor between them, the adjacentwalls of the parts being substantially parallel for a length suflicient for the formation of a gradually expanding chamber simulating the delivery end of a Venturi tube, the relative positions of the parts along the axis determining the area of the annular space between the parts, the inner art being provided with openings for tie delivery of an emulsion of fuel and air into the annular space at a position of the highest suction in said space caused by the flow of air therethrough.

10. A. carburetor having an air entrance passageway having a side wall which llarcs to gradually enlarge the passageway in the direction of flow of air therethrough, a hollow valve member automatically longitudinally movable in said passageway responsive to changes in suction in its interior and having-an external side wall lying adjacent the internal flaring side wall of the passageway and forming between the wall of the valve member and the internal wall of the passageway a space which enlarges gradually in thedirection of air flow ill means within the valve member to deliver I a mixture of fuel and air to said space slightly posterior to the smallest cross sectional area thereof.

ll. A. carburetor having an air induction passage comprising an external member having an opening therethrough which. gradually flares in the direction of flow of air therethrough, a valve member automatically longitudinally movable within the external member and along the common axis of the valve member and the external member, said valve member having wall which flares outwardly in the direc' on of the flow or hus forming a space between the external member and the valve member. the cross sectional of which raduallv enlarges in the irection or new ct l suhsta "ally e same ratio men s that or the delivery of turi tube, and means within the valve member for delivering fuel and air to the space between the valve member and the external member at a point near the smallest cross sectional area of said space for all positions of the valve member, suction insaid means serving to open said valve.

12. In a carburetor, a fuel feedingVenturi tube, a second Venturi tube augmenting the suction thereof, and a connection between said Venturi tubes automatically movable along said second Venturi tube and having means to feed the fuel from the delivery end of the first Venturi tube to the second Venturi tube always at substantially the region of highest suction in the latter.

13. In a carburetor, a hollow valve member having a portion shaped like the frustrum of a cone and with the small end projecting outwardly, a surrounding wall with respect to which the valve member moves under influence of its internal suction, said wall being substantially parallel with the external wall of the valve member thus during operation forming an annular space between the valve member and the wall which gradually increases in area from the small part of thevalve member toward the large part thereof, and means within the valve for feeding a mixture of fuel and air into the space between the valve and the wall at a point near the small end of the valve.

14. In a carburetor, a valve member having a portion shaped like the frustrum of a cone and with the small end projecting outwardly, a surrounding wall with respect to which the valve member moves, said wall being substantially parallel with the. external wall ofthe valve member thus during operation forming an annular space between the valve member and the wall -which gradually increases in area from the small part of the valve toward the large part thereof, means within the valve for feeding a mixture of fuel and air into the space between the valve and the wall at a point near the small end of the valve, and achamber in the valve for receiving suction from said means for opening the valve.

15. In a carburetor, a valve member having a portion shaped like the frustrum of a cone and with the small end projecting outwardly, a surrounding wall with respect to which the valve member moves, said wall being substantially parallel with the external wall of the valve member thus during operation forming an annular space between the valve member and the wall which gradually increases in area from the small part of the valve toward'the large part thereof, means Within the valve for feeding a mixture of fuel and air into the space between the valve and the wall at a point near the small end of the valve, a chamber within the valve adapted to receive liquid fuel, and

, a piston operable in the fuel in said chamber for damping the vibrations of the valve. 16. In a carburetor, an automatically movable valve member constituting a secondary air intake restriction, a Well within said valve member, a piston operating in said well, means to communicate suction to said well to assist in opening said valve and meansto deliver fuel into said well, said well and piston forming a dash pot to prevent vibration of said valve member.

17. In a carburetor having fuel and air inlet means, the combination with a fuel chamber of a. small Venturi tube extending into the interior of the carburetor, and having its throat connected with the upper spaces ofthe fuel chamber for the creation of a partial vacuum therein for lifting fuel, a movable plunger within the carburetor constituting in part a secondary air intake a valve, said plunger having a contoured portion adapted to move opposite the inner end of said Venturi tube and to variably obstruct the flow of airthrough said Venturi tube', depending upon the degree of opening of the secondary air intake valve whereby the degree of partial vacuum in the float chamber may be regulated.

' 18. In a carburetor having air inlet means, the combination with a body portion of a small Venturi tube extending from atmosphere into said body portion. a fuel chamber, a duct connecting the throat of said Venturi tube with the upper spaces of the fuel chamber for lifting fuel thereto, a choke adapted to be moved over the external end of said Venturi tube for regulating the amount of air flow throughthe Venturi tube, manual means for adjusting said choke for securing different degrees of suction on the fuel in the float chamber, and a nozzle in the carburetor connected with the lower part of the float chamber for delivering fuel therefrom, the position of said choke determining the quantity of fuel delivered.

19. In a carburetor, a fuel feeding Venturi tube, a second Venturi tube into which said first mentioned Venturi tube discharges its mixture, a plunger forming a mixture passageway between said Venturi tubes, said plunger being adapted to reciprocate longi-' tudinally within the second of said tubes in response to varying engine demands, and

being so shaped With respect to the Venturi tube Within which itreciprocates as to always deliver the mixture thereto at the point of greatest suction therein.

20. In a carburetor, a fuel feeding Venturi tube, a second Venturi tube, a reciproeating plunger adapted to move longitudinally within said second Venturi tube. amixture passage-way in said plunger leading from said first mentioned Venturi tube to said second Venturi tube, the movement of said' plunger determining the location of lifting suction in the upper part of the float chamber, a fuel feeding nozzle for delivering fuel from the bottom of the float chamber, a second Venturitube, a reciprocating member movable longitudinally-Vin said second Venturi tube and serving to change the location of the point of greatest suction therein, a mixture passage-way carried by said reciprocating member and extending between said nozzle and said second Venturi tube, the delivery end of said passage-way always registering with the point of greatest suction in said second Venturi tube, and means responsive to the movement of said reciprocating member for varying the efl'ectiveness of said vacuum Venturi tube and thus preventing objectionable variation of the suction in the upper part of the float chamber.

22. In a carburetor, a fuel reservoir, a vacuum Venturi tube for creating a fuel lifting suction in the upper part of the fuel reservoir, a second Venturi tube for feeding fuel from the lower part of the fuel reservoir, a third Venturi tube into which the primary mixture of fuel and airis delivered from said second Venturi tube, a plunger movable upon the discharge end of said second Venturi tube and reciprocating withv in said third Venturi tube, said plunger in its movement serving to locate the point of greatest suction in'said'third Venturi tube and to deliver the primary mixture thereto eanna? always at that point, and means controlled by said plunger for varying the effectiveness of said vacuum Venturi tube and thus preventing variation in suction in the upper part of the float chamber.

23. In a carburetor, a fuel reservoir, a

- take passage of the carburetor, and the plunger therein being adapted. to rise in response to increased engine demands, a fuel passageway through said plunger for the primary mixture, the point of greatest suction in said third Venturi tube being located at the discharge end of said passage-way regardless of the position of the plunger therein, said dash-pot giving a rich mixture of fuel in response to sudden engine demands asthe plunger rises, and means controlled by the movement of the plunger for varying the efiiciency of said vacuum Venturi tube.

In witness whereof, I hereunto subscribe my name this 27th day of April, 1921.. MILFORD G. CHANDLER) Witnesses:

Arum C. AHLBERG, EMILE J. Bonnsnors. 

